1. Field
Exemplary embodiments of the present invention relate to a decoding circuit and a method of decoding a signal.
2. Description of the Related Art
Pulse width modulation (PWM) is a method of modulating the pulse width of a transmission signal (hereinafter called a “PWM signal”) according to a logic value of “0” or “1”. The PWM signal periodically switches between a low level and a high level. A rising or falling edge of the PWM signal may be controlled based on the logic value of data transferred through the PWM signal.
FIGS. 1A and 1B are respectively a block diagram and a waveform diagram illustrating a method of sending and receiving signals using PWM.
Referring to FIG. 1A, a PWM signal S is transmitted from a transmission unit 110 to a reception unit 120. Referring to FIG. 1B, a rising edge of the PWM signal S changes based on a logic value of data to be transmitted. A section TDATA denotes a period in which 1-bit data is transmitted in the PWM signal S. A position of the rising edge of the PWM signal S is determined based on the logic value of data to be transmitted.
When data “0” is to be transmitted, a low level section TL is shorter than a high level section TH. When data “1” is to be transmitted, a high level section TH is longer than a low level section TL. That is, when data “0” is to be transmitted, a rising edge R1 is placed behind a middle point C of the section TDATA in which the data “0” is transmitted. When data “1” is to be transmitted, a rising edge R2 is placed ahead of the middle point C of the section TDATA in which the data “1” is transmitted. When the transmission unit 110 sends the PWM signal S as described above, the reception unit 120 may receive the PWM signal S and convert it into a digital value.
When the reception unit 120 converts the PWM signal S into an accurate digital value using a PWM method, it is important to accurately detect the position of the rising edge.